The inhibitory effect of the lens and the aqueous humor in lens regeneration in adult newts offers an excellent opportunity for the study of the inhibition of metaplasia. The experiment is designed to find out if the lens and the aqueous humor of the adult newts is the common inhibitor for lens, limb, and tail regeneration by the following methods: 1. Collection of aqueous humor by withdrawing daily from the anterior chamber of the eyes with a microsyringe. 2. Administration of aqueous humor daily to the newts with limbs or tails removed. 3. Implantation of newts lenses to the newts with limbs or tails removed. This experiment is designed to find out if the dorsal iris epithelial cells exert any dominance effect over the ventral iris cells and inhibit the ventral iris cells from regenerating a lens. The animals are lentectomized and divided into two groups: 1. One group with the mid-dorsal iris removed. 2. One group with the whole dorsal iris removed.